21000929121 has 12 divisors (see below), whose sum is σ = 31931237520. Its totient is φ = 13263744600.

The previous prime is 21000929099. The next prime is 21000929129. The reversal of 21000929121 is 12192900012.

It is not a de Polignac number, because 21000929121 - 2⁹ = 21000928609 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21000929129) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 61406055 + ... + 61406396.

It is an arithmetic number, because the mean of its divisors is an integer number (2660936460).

Almost surely, 2^21000929121 is an apocalyptic number.

It is an amenable number.

21000929121 is a deficient number, since it is larger than the sum of its proper divisors (10930308399).

21000929121 is a wasteful number, since it uses less digits than its factorization.

21000929121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122812476 (or 122812473 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The spelling of 21000929121 in words is "twenty-one billion, nine hundred twenty-nine thousand, one hundred twenty-one".